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RP (Rapid Prototyping)

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(1)446.326A CAD/CAM. RP (Rapid Prototyping). November 05, 2008 Sung-Hoon Ahn School of Mechanical and Aerospace Engineering Seoul National University. (2) MRI 1. 3. 8. (3) From 2D to 3D printing. 2D sheet. 2.5D Prismatic plate. 3D structure. (4) NASA: Printing in Space. Emergency in 2008 summer. FDM1600 test at zero gravity Johnson Space Center & Marshall Space Flight Center 2000. (5) Requirements in Product Development ο‚§ Functional or aesthetic assessment ο‚§ Communication aids, visualization ο‚§ Assemblability checking ο‚§ 25 or 30% of product development budget are spent on physical prototypes and testing ο‚§ Rapid Prototyping fabricates a part of arbitrary shape directly from CAD model by forming thin layers of the part layer by layer. (6) Introduction to RP ο‚§ Other name of RP - Layered Manufacturing - Rapid Prototyping and Manufacturing - Solid Freeform Fabrication (SFF). ο‚§ Group of related technologies that are used to fabricate physical objects directly from CAD data ο‚§ Add and bond materials in layers to form objects ο‚§ Offer advantages compared to classical subtractive fabrication methods. (7) Advantages of RP ο‚§ No need to define a blank geometry ο‚§ No need to define set-ups and material handling ο‚§ No need to consider jigs, fixtures, and clamping ο‚§ No need to design mold and die. (8) General System Configuration of RP. (9) Stereo Lithography Process ο‚§ Geometry Input : STL file format - Developed for STereo Lithography - De facto standard for RP data - Most CAD systems support STL format. (10) Stereo Lithography Process (cont.) ο‚§ STL file formats. (a) ASCII. (b) Binary. (11) Typical Errors in STL file. (12) Stair-Step Effect. Surface roughness vs. build time. (13) Support Structures. (14) Issues in RP ο‚§ Accuracy and Surface Finish ο‚§ Material - Stereo Lithography Resins - Metals - Ceramics and Paper. ο‚§ Cost - Equipment - Maintenance. ο‚§ Time. (15) 1. Stereo Lithography Apparatus (SLA) ο‚§ Developed by 3D Systems, Inc. ο‚§ Laser beam will scan the surface following the contours of the slice. SLA-3500. (16) Micro SLA Part Gear. Horse. Turbine. Dog. (17) 2. Selective Laser Sintering (SLS) ο‚§ Developed by The University of Texas at Austin. ο‚§ Powders are spread over a platform by a roller ο‚§ A laser sinters selected areas causing the particles to melt and then solidify. (18) 3. Laminated Object Modeling (LOM) ο‚§ Developed by Helysis ο‚§ The undersurface of the foil has a binder that when pressed and heated by the roller causes it to glue to the previous foil. ο‚§ The foil is cut by a laser following the contour of the slice. Helisys 2030E LOM machine Part envelope size 32"x22"x20". (19) LOM based technique ο‚§ Paper Lamination Technology(PLT) System. < Kira Solid Center > - Type: PLT-A4 - Model Material: Exclusive use sheet paper (280Γ—190 Γ—200m) - Paper Thickness: 0.08mm, 0.15mm - Resolution: Β±0.05mm (X, Y), Β±0.1mm (Z) - Accuracy: Β±0.2mm. (20) 4. Fused Deposition Modeling (FDM). (21) Fused Deposition Modeling (FDM). (22) FDM Head. x-axis track heating units. model head support head. z-axis track. foam bed. (23) 5. 3D Printers ο‚§ Developed at MIT ο‚§ Parts are built upon a platform situated in a bin full of powder material.. (24) 3D Printing Process. 3-D printing method developed by Sachs and colleagues (2000). (25) 6. Solid Ground Curing (SGC) ο‚§ ο‚§ ο‚§ ο‚§. Developed and commercialized by Cubital Ltd. (Israel) Uses a Photopolymer, sensitive to UV-light The vat moves horizontally as well as vertically The horizontal movements take the workspace to different stations in the machine. (26) 7. Shape Deposition Manufacturing (SDM) ο‚§ Developed by Stanford University/CMU ο‚§ Uses deposition and milling ο‚§ Provides good surface finish. (27) Issues in RP Materials ο‚§ Rapid Fabrication of functional parts - Structural - Optical - Surface Roughness - Electrical - Thermal - Color - ………. (28) FDM Software – Three Levels ο‚§ STL file – Tessellated Stereolithography file – export from solid modeling package ο‚§ SSL file – Sliced Layer File, Support Calculation – Proper part orientation can drastically affect build time, support requirements, and part strength. ο‚§ SML file – Raster, Build Parameters, time estimation. (29) Case study: Collapsible Shovel Head 1. Tessellated (Triangulated) format 4. Road Generation. 2. Vertically Sliced File 5. SML firle. 3. Support Calculation. (30) FDM Build Parameters - Software ο‚§ Perimeters, Contours, Raster (Road type) - Perimeter: Follows outer shape of current slice - ideal for cosmetic. outer surface - Contour: Follows shape of perimeter on part interior - not commonly used as it leaves gaps - Raster: Standard back and forth part fill - adds strength to part, composite theory (raster angles). ο‚§ Road width - Dependant on nozzle size and feed rate - ranges from .012 to .0396 for T12 nozzle. ο‚§ Air Gap - Gap between roads - allows for tightly fused, strong surface, or sparse, quick building fill. (31) Micro Structure of FDM. (32) Part Post-process of FDM. FDM Process. Assembled Part. (33) Resin Infiltration. Raw FDM ABSi. During Infiltration Raw material. 0.6. Infiltration. Infiltration+Sanding. 25. 0.5. Transmissivity(%). Transmissivity(%) .. After Infiltration. 0.4 0.3 0.2 0.1. 20 15 10 5 0. 0 800 760 720 680 640 600 560 520 480 440 400. Wave length(nm). -0.003. 0 Air Gap(inch). 0.003. (34) Flash Memory Reader. CATIA modeling:. FDM process:. 5 hours. 10 hours. Post-process : 24 hours Total prototyping time : 39 hours. (35) Gallery ο‚§ SLA. (36) Gallery (cont.) ο‚§ FDM. (37) Gallery (cont.) ο‚§ FDM. GPS module for PDA. (38) Gallery (cont.) ο‚§ Z- corp (3D Printer). ο‚§ SLS. (39) Gallery (cont.) ο‚§ Z- corp (3D Printer). (40) Gallery (cont.) ο‚§ Z- corp (3D Printer). (41) Gallery (cont.) ο‚§ Z- corp (3D Printer). (42) Applications ο‚§ Architectures. A machine mounted on rails might be used to build multiple houses. (43) Applications (cont.) ο‚§ Materialization of arts. Lifting the kouros out of the Mammoth. The original Volomandra Kouros and the SLA replica. (44) Applications (cont.) ο‚§ Medical Domain. Before surgery. After surgery. CT Scan. RP part. Virtual surgery. (45) MRP (Medical rapid prototyping) ο‚§ 3D model creation process 3D Digital Image. Data transfer process. Evaluation of Design :Using CAD Program. RP Medical model validation. RP Medical model production. (46) Tissue Engineering Vacanti, et al. Yan, et al. CAD modeling. RP part. Rehabilitated ear. (47) Applications (cont.) ο‚§ Micro component. Micro robot by Sandia Lab. (48) Applications (cont.) ο‚§ Rapid Tooling (RT). Core and cavity sets produced by RapidTool β„’. DTM's RapidToolβ„’ process for rapid mold making. (49) Applications (cont.) ο‚§ Other Examples Patterning with Ceramic. Sensor and Actuator. Artificial Bone and Ear. Electrode ; A. Safari et al. IEEE Artificial bone P. Kumar at al, Ann Arbor. Microreactor Y. Tan et al. Am. Ceram. Soc.. PZT Sensor ; J. E. Smay et al. J. Am. Ceram. Soc. R. Knitter at al. RP Journal. Artificial ear Bio-compatible Material. (50) 3D Nano/Micro Parts ο‚§ Two-photon Stereolithography (a). (b). SEM images of fabricated islands with (a) actual and (b) exaggerated ratio of height vs. width by controlling both exposure time and laser power simultaneously. Inse t is top v iew of th e s tructure. Fabricated micro-prototypes of a micro rotor. SEM images of fabricated micro-Thinker by doublescanning path. The insets are the same micro-Thinker with various view angles, and the scale bars are 10 γŽ›. (51) Hybrid RP System ο‚§ Hardware οƒΌ Deposition; Rapid Prototyping. Z axis control. οƒΌ Cutting; Milling οƒΌ Hybrid; Both. High speed spindle. Dispenser UV lamp. Microscope. Micro needle. Micro needle. Micro endmill. Micro endmill SPECIFICATIONS. X and Y axis control Granite Base. 3 Axes-stage Dispenser Micro needle Micro tool High speed spindle UV curing system Controller. 1γŽ› resolution 15 ~ 700 kPa  140 γŽ› ~ 800 γŽ›  100 γŽ› ~ 1000 γŽ› Max. 46,000rpm 0 ~ 400 W, Ξ» = 365 ㎚ PMAC (Multi-tasking board). (52) Hybrid RP System (cont.) ο‚§ Hybrid process: depositing + machining. High speed spindle. Air cylinder. Micrometer. Barrel I. Barrel II. Micro needle. Micro tool. Conceptual process of NCDS. (53) Hybrid RP System (cont.) ο‚§ Process planning Deposition. 3D MODEL. Machining. SLICING Part material. NO. DEPOSITION. DEPOSITION. CURING. CURING. HYBRID SYSTEM. CONVENTIONAL DEPOSITON SYSTEM. PROCESS PLANNING. MACHINING. LAST LAYER ? YES. LAST LAYER ?. POST-PROCESS. Support material. Deposition and Machining. Machining. NO. Molding / Casting. Support. YES 3D PART. Part Deposition. Machining Heat Demolding. (54) 90mm. CAD Model and NC Codes Slicing: Slice into 9 layers, layer thickness is 10mm. 90mm. Layer model of a microcone. CAD design of a microcone. Hatching: Parallel line spacing, filling between lines is 10mm. (55) NC Codes for the Cone. Layer 1. Layer 9 Layer 8 Layer 7 Layer 6 Layer 5 Layer 4 Layer 3 Layer 2 Layer 1. (56) Nano Composite Parts ο‚§ Micro Gear A gear geometry with  2.9mm was fabricated - 5wt% MWCNT + Acrylic resin - Dispensing process using  300γŽ› needle micro milling using  100γŽ› flat endmill -. ο‚§ Stapes The smallest bone in human body, width 2.5mm / height 3.5mm - 40wt% Hydroxyapatite + Acrylic resin - Dispensing process using  140γŽ› needle micro milling using  100γŽ› flat endmill - Mold (using wax) machining β†’ part deposition β†’ surface machining β†’ demolding -. 3.4mm. Microscope picture of microgear. ο‚§ Fabrication time Parts. Average Time (min). Micro Gear. 2. Stapes. 15. 3.0mm. Geometry of stapes. (57) Scaffold for Bone Growth ο‚§ Bio-degradable polymer. PLGA 85/15. PLGA 85/15 + 10wt% HA. Size; Ξ¦ 5mm Γ— 10mm. (58) Drug Delivery System (DDS) ο‚§ Specimen for Zero-order Release Test Burst. Drug Delivery Device. Container. ο‚§ Scaffold Shape of DDS (Controlled Pore Size). Fabricated container and drug delivery device. Fabricated drug delivery device of scaffold shape (15 layers, [0˚8/90˚7], 5mmΓ—5mm). (59) DDS (cont.) ο‚§ In vivo test with Sprague-dawley Rat 1. Sprague-dawley Rat. 2. Anesthetize mouse. Anesthesia When implantation (100㎎/㎏ for Sprague-dawley Rat) - 25㎎ of Ketamine(90vol%)+Xylazine(10vol%) - 1 γŽ– needle. When picking the specimen - Inhale anesthetize using ether. 3. Remove hairs. Incise back skin. (60) DDS (cont.) ο‚§ Implantation of DDS - Scaffold type of DDS -  2mm Γ— 2mm size of DDS for implantation. 5-FU/PLGA/HA. - 5-FU(10wt%)/PLGA(85:15)(85wt%)/HA(5wt%). Schematic diagram of scaffold shape of DDS for in vivo. 4. 6. 5. Prepare scaffold DDS. Insert the scaffold. Suture the skin. (61) DDS (cont.) ο‚§ Collecting implanted DDS form Sprague-dawley rat (a). (b) 40. (c). Cumulative amount of released drug (%). Cylinder Scaffold 30. 20. 10. 0 0. 5. 10. 15. T ime (days). (a) Resection of back skin of the rat, (b) DDS in the back of the rat, and (c) DDS in resected skin. (62)

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